Income Taxes

9 Months Ended

Sep. 30, 2014

Income Taxes [Line Items]

Income Taxes

INCOME TAXES

Income Tax Rates - The provision for income taxes for earnings from continuing operations is based on an estimated annual effective income tax rate that excludes the impact of significant unusual or infrequently occurring items, discontinued operations or extraordinary items. The overall income tax rates shown in the following table were computed by dividing income tax expense (benefit) by income from continuing operations before income taxes.

	Alliant Energy				IPL				WPL
Three Months Ended September 30	2014		2013		2014		2013		2014		2013
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%
IPL’s tax benefit riders	(13.0	)	(12.9	)	(39.2	)	(38.9	)	—		—
Effect of rate-making on property-related differences	(8.6	)	(6.2	)	(22.4	)	(16.5	)	(0.8	)	(1.4	)
Production tax credits	(6.8	)	(7.7	)	(9.3	)	(10.6	)	(6.2	)	(6.6	)
Other items, net	0.7		1.6		2.2		0.4		—		3.7
Overall income tax rate	7.3	%	9.8	%	(33.7	%)	(30.6	%)	28.0	%	30.7	%

	Alliant Energy				IPL				WPL
Nine Months Ended September 30	2014		2013		2014		2013		2014		2013
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%
IPL’s tax benefit riders	(12.4	)	(12.6	)	(36.5	)	(37.8	)	—		—
Effect of rate-making on property-related differences	(6.7	)	(5.9	)	(18.4	)	(16.1	)	(0.7	)	(0.8	)
Production tax credits	(6.6	)	(7.7	)	(8.8	)	(10.4	)	(6.2	)	(6.9	)
Other items, net	2.9		2.6		3.2		0.8		3.0		4.4
Overall income tax rate	12.2	%	11.4	%	(25.5	%)	(28.5	%)	31.1	%	31.7	%

IPL’s tax benefit riders - Alliant Energy’s and IPL’s effective income tax rates include the impact of reducing income tax expense with offsetting reductions to regulatory liabilities as a result of implementing IPL’s tax benefit riders. Refer to Note 2 for additional details of the tax benefit riders.

Effect of rate-making on property-related differences - Alliant Energy’s and IPL’s effective income tax rates are impacted by certain property-related differences for which deferred tax is not recognized in the income statement pursuant to rate-making principles, substantially all of which relates to IPL. The increased benefits from property-related differences recognized during the three and nine months ended September 30, 2014 was primarily due to additional deductions from the allocation of mixed service costs related to Marshalltown.

Production tax credits - For the three and nine months ended September 30, details regarding production tax credits (net of state tax impacts) related to various wind projects are as follows (dollars in millions):

	End of Production	Nameplate	Three Months				Nine Months
	Tax Credit Generation	Capacity in MW	2014		2013		2014		2013
Cedar Ridge (WPL)	December 2018	68		$0.6		$0.6		$2.8		$2.9
Bent Tree - Phase I (WPL)	February 2021	201	2.0		2.2		9.4		9.2
Subtotal (WPL)			2.6		2.8		12.2		12.1
Whispering Willow - East (IPL)	December 2019	200	2.0		2.3		9.8		10.3
				$4.6		$5.1		$22.0		$22.4

Deferred Tax Assets and Liabilities - For the nine months ended September 30, 2014, Alliant Energy’s, IPL’s and WPL’s non-current deferred tax liabilities increased $177.6 million, $123.6 million and $54.6 million, respectively. These increases in non-current deferred tax liabilities were primarily due to property-related differences recorded during the nine months ended September 30, 2014, including tax accounting method changes for cost of removal expenditures and generation repairs, which are discussed in Note 2.

Carryforwards - At September 30, 2014, tax carryforwards and associated deferred tax assets and expiration dates were estimated as follows (dollars in millions):

Alliant Energy	Carryforward Amount		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$710		$244	2029
State net operating losses	744		37		2018
Federal tax credits	193		190		2022
				$471

IPL	Carryforward Amount		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$310		$106	2029
State net operating losses	217		11		2018
Federal tax credits	64		63		2022
				$180

WPL	Carryforward Amount		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$305		$105	2029
State net operating losses	116		6		2018
Federal tax credits	71		69		2022
				$180

IPL [Member]

Income Taxes [Line Items]

Income Taxes

INCOME TAXES

Income Tax Rates - The provision for income taxes for earnings from continuing operations is based on an estimated annual effective income tax rate that excludes the impact of significant unusual or infrequently occurring items, discontinued operations or extraordinary items. The overall income tax rates shown in the following table were computed by dividing income tax expense (benefit) by income from continuing operations before income taxes.

	Alliant Energy				IPL				WPL
Three Months Ended September 30	2014		2013		2014		2013		2014		2013
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%
IPL’s tax benefit riders	(13.0	)	(12.9	)	(39.2	)	(38.9	)	—		—
Effect of rate-making on property-related differences	(8.6	)	(6.2	)	(22.4	)	(16.5	)	(0.8	)	(1.4	)
Production tax credits	(6.8	)	(7.7	)	(9.3	)	(10.6	)	(6.2	)	(6.6	)
Other items, net	0.7		1.6		2.2		0.4		—		3.7
Overall income tax rate	7.3	%	9.8	%	(33.7	%)	(30.6	%)	28.0	%	30.7	%

	Alliant Energy				IPL				WPL
Nine Months Ended September 30	2014		2013		2014		2013		2014		2013
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%
IPL’s tax benefit riders	(12.4	)	(12.6	)	(36.5	)	(37.8	)	—		—
Effect of rate-making on property-related differences	(6.7	)	(5.9	)	(18.4	)	(16.1	)	(0.7	)	(0.8	)
Production tax credits	(6.6	)	(7.7	)	(8.8	)	(10.4	)	(6.2	)	(6.9	)
Other items, net	2.9		2.6		3.2		0.8		3.0		4.4
Overall income tax rate	12.2	%	11.4	%	(25.5	%)	(28.5	%)	31.1	%	31.7	%

IPL’s tax benefit riders - Alliant Energy’s and IPL’s effective income tax rates include the impact of reducing income tax expense with offsetting reductions to regulatory liabilities as a result of implementing IPL’s tax benefit riders. Refer to Note 2 for additional details of the tax benefit riders.

Effect of rate-making on property-related differences - Alliant Energy’s and IPL’s effective income tax rates are impacted by certain property-related differences for which deferred tax is not recognized in the income statement pursuant to rate-making principles, substantially all of which relates to IPL. The increased benefits from property-related differences recognized during the three and nine months ended September 30, 2014 was primarily due to additional deductions from the allocation of mixed service costs related to Marshalltown.

Production tax credits - For the three and nine months ended September 30, details regarding production tax credits (net of state tax impacts) related to various wind projects are as follows (dollars in millions):

	End of Production	Nameplate	Three Months				Nine Months
	Tax Credit Generation	Capacity in MW	2014		2013		2014		2013
Cedar Ridge (WPL)	December 2018	68		$0.6		$0.6		$2.8		$2.9
Bent Tree - Phase I (WPL)	February 2021	201	2.0		2.2		9.4		9.2
Subtotal (WPL)			2.6		2.8		12.2		12.1
Whispering Willow - East (IPL)	December 2019	200	2.0		2.3		9.8		10.3
				$4.6		$5.1		$22.0		$22.4

Deferred Tax Assets and Liabilities - For the nine months ended September 30, 2014, Alliant Energy’s, IPL’s and WPL’s non-current deferred tax liabilities increased $177.6 million, $123.6 million and $54.6 million, respectively. These increases in non-current deferred tax liabilities were primarily due to property-related differences recorded during the nine months ended September 30, 2014, including tax accounting method changes for cost of removal expenditures and generation repairs, which are discussed in Note 2.

Carryforwards - At September 30, 2014, tax carryforwards and associated deferred tax assets and expiration dates were estimated as follows (dollars in millions):

Alliant Energy	Carryforward Amount		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$710		$244	2029
State net operating losses	744		37		2018
Federal tax credits	193		190		2022
				$471

IPL	Carryforward Amount		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$310		$106	2029
State net operating losses	217		11		2018
Federal tax credits	64		63		2022
				$180

WPL	Carryforward Amount		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$305		$105	2029
State net operating losses	116		6		2018
Federal tax credits	71		69		2022
				$180

WPL [Member]

Income Taxes [Line Items]

Income Taxes

INCOME TAXES

Income Tax Rates - The provision for income taxes for earnings from continuing operations is based on an estimated annual effective income tax rate that excludes the impact of significant unusual or infrequently occurring items, discontinued operations or extraordinary items. The overall income tax rates shown in the following table were computed by dividing income tax expense (benefit) by income from continuing operations before income taxes.

	Alliant Energy				IPL				WPL
Three Months Ended September 30	2014		2013		2014		2013		2014		2013
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%
IPL’s tax benefit riders	(13.0	)	(12.9	)	(39.2	)	(38.9	)	—		—
Effect of rate-making on property-related differences	(8.6	)	(6.2	)	(22.4	)	(16.5	)	(0.8	)	(1.4	)
Production tax credits	(6.8	)	(7.7	)	(9.3	)	(10.6	)	(6.2	)	(6.6	)
Other items, net	0.7		1.6		2.2		0.4		—		3.7
Overall income tax rate	7.3	%	9.8	%	(33.7	%)	(30.6	%)	28.0	%	30.7	%

	Alliant Energy				IPL				WPL
Nine Months Ended September 30	2014		2013		2014		2013		2014		2013
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%	35.0	%
IPL’s tax benefit riders	(12.4	)	(12.6	)	(36.5	)	(37.8	)	—		—
Effect of rate-making on property-related differences	(6.7	)	(5.9	)	(18.4	)	(16.1	)	(0.7	)	(0.8	)
Production tax credits	(6.6	)	(7.7	)	(8.8	)	(10.4	)	(6.2	)	(6.9	)
Other items, net	2.9		2.6		3.2		0.8		3.0		4.4
Overall income tax rate	12.2	%	11.4	%	(25.5	%)	(28.5	%)	31.1	%	31.7	%

IPL’s tax benefit riders - Alliant Energy’s and IPL’s effective income tax rates include the impact of reducing income tax expense with offsetting reductions to regulatory liabilities as a result of implementing IPL’s tax benefit riders. Refer to Note 2 for additional details of the tax benefit riders.

Effect of rate-making on property-related differences - Alliant Energy’s and IPL’s effective income tax rates are impacted by certain property-related differences for which deferred tax is not recognized in the income statement pursuant to rate-making principles, substantially all of which relates to IPL. The increased benefits from property-related differences recognized during the three and nine months ended September 30, 2014 was primarily due to additional deductions from the allocation of mixed service costs related to Marshalltown.

Production tax credits - For the three and nine months ended September 30, details regarding production tax credits (net of state tax impacts) related to various wind projects are as follows (dollars in millions):

	End of Production	Nameplate	Three Months				Nine Months
	Tax Credit Generation	Capacity in MW	2014		2013		2014		2013
Cedar Ridge (WPL)	December 2018	68		$0.6		$0.6		$2.8		$2.9
Bent Tree - Phase I (WPL)	February 2021	201	2.0		2.2		9.4		9.2
Subtotal (WPL)			2.6		2.8		12.2		12.1
Whispering Willow - East (IPL)	December 2019	200	2.0		2.3		9.8		10.3
				$4.6		$5.1		$22.0		$22.4

Deferred Tax Assets and Liabilities - For the nine months ended September 30, 2014, Alliant Energy’s, IPL’s and WPL’s non-current deferred tax liabilities increased $177.6 million, $123.6 million and $54.6 million, respectively. These increases in non-current deferred tax liabilities were primarily due to property-related differences recorded during the nine months ended September 30, 2014, including tax accounting method changes for cost of removal expenditures and generation repairs, which are discussed in Note 2.

Carryforwards - At September 30, 2014, tax carryforwards and associated deferred tax assets and expiration dates were estimated as follows (dollars in millions):

Alliant Energy	Carryforward Amount		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$710		$244	2029
State net operating losses	744		37		2018
Federal tax credits	193		190		2022
				$471

IPL	Carryforward Amount		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$310		$106	2029
State net operating losses	217		11		2018
Federal tax credits	64		63		2022
				$180

WPL	Carryforward Amount		Deferred Tax Assets		Earliest Expiration Date
Federal net operating losses		$305		$105	2029
State net operating losses	116		6		2018
Federal tax credits	71		69		2022
				$180